Dual fuel engine



Aug. 17, 1954 V. C. REDDY El' AL DUAL FUEL ENGINE Filed Deo. 9, 1950 4 Sheets-Sheet 1 Aug- 17, 1954 v. c. REDDY ErAL 2,686,503

. DUAL FUEL ENGINE Filed Dec. 9, 1950 4 Sheets-Sheet 2 :inventors Cttornegs Aug. 17, 1954 v. c. REDDY ETAL 2,686,503

DUAL FUEL ENGINE Filed Dec. V9, 195o 4 Sheets-Sheet 3 lSnventors attorneys @my mw@ .i

Aug. 17, 1954 v. c. REDDY ETAL DUAL FUEL ENGINE `4 Sheets-Sheet 4 Filed Dec. 9, 1950 :inventors Q23/ .s .efzfaw Gttornegs A W, Il. fwunnnwnwwwj; u Il NS J i. w W, PMN V f. f... l y w w 4. l u N NIILYIv/u f i ZMWMAWA// Patented Aug. 17, 1954 DUAL FUEL ENGINE Virgin C. Reddy, Farmington, and Roger H. Harrison, Detroit, Mich., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application December 9, 1950, Serial No. 200,084

(Cl. 12S- 27) 13 Claims. l

This invention generally relates to internal combustion engines of the diesel or compression ignition type and more particularly to dual fuel engines and the fuel supply and control means therefore whereby a two-cycle compression ignition engine is adapted to operate on either gas fuel, with a small amount of oil injected to cause ignition, orto operate on oil fuel alone as a diesel engine when gas fuel is not available.

Dual fuel engines are used where inexpensive gas fuels are readily obtainable and, upon a failure in the gas supply, the engine is automatically caused to operate as a straight diesel engine until the gas supply is again available.

The principal object of the present invention is to provide simple means for introducing gas fuel into the engines cylinder and for automatically controlling the supply of both the gas fuel and oil fuel into the cylinder of a two-cycle diesel engine in which charging and scavenging air is supplied by `an engine driven blower in amounts greater than required by the engine throughout the available speed range, whereby the engine is caused to operate on dual fuel when gas fuel is available and to operate on oil fuel when there is a failure in the gas supply.

The combined means by which this object is accomplished will become apparent by reference to the following detailed description and accompanying drawings illustrating Ithese combined means and the arrangement thereof.

Figure l is a transverse cross sectional elevation View through an engine cylinder with parts shown broken away.

Figure 2 is an enlarged view of a detail shown in Figure l.

Figure 3 is a, longitudinal cross sectional elevation View of the engine governor and fuel control means operated thereby, with parts shown broken away and in sections.

Figure 4 is an enlarged cross sectional View taken on line 4 4 of Figure 3.

Figure 5 is a sectional view taken on line 5-5 of Figure 3.

Figure 6 is an enlarged cross sectional elevation view of one of the unit fuel oil injection pumps shown in Figure l.

Figure 7 is an enlarged developed view of the plunger of the injection pump shown in Figure 6.

Figure 8 is a schematic view of the gas fuel supply connections for the engine, including protective, gas pressure regulating and engine governor operated gas supply control means.

Figure 9 is a cross sectional elevation view of a detail shown in Figure 8.

The engine fuel and air supply means is best illustrated in Figure 1. The engine includes a cylinder block l provided with an air box cavity 3, a cylinder bore 5 extending therethrough and having water jacket spaces 6 around the bore and a circumferential air supply groove 1 extending from the air box cavity 3 through the water jacket spaces and into the bore 5 intermediate of the ends thereof. A blower of the Roots type, generally indicated by the character reference 8 and having a housing 9 is mounted on the side of the cylinder block I. The housing 9 of the Roots blower is provided with an atmospheric' air inlet opening Il, a pressure outlet opening I3 which registers with an air inlet opening I4 of the air box cavity 3 of the cylinder block I. Two blower rotors I5 and I 1 are rotatably mounted Vin the blower housing 9 and are driven in conventional manner by the engine by means of timing gears, not shown, so that charging and scavenging air is supplied to Ithe air box under pressure in excess of the quantity required by the engine cylinders for all available engine speeds. It will be evident that the air pressure from the blower 3 increases with the speed of the engine and blower rotors I5 and Il driven thereby.

A cylinder liner I9 is pressed in each bore 5 of the cylinder block I and each cylinder liner is provided with a circumferentially extending row of charging and scavenging air ports 2I registering with the air supply groove 1 in the engine block opening into the air box cavity 3.

A piston 23 is reciprocal in each cylinder liner and is connected by a connecting rod 24 to one throw of the engine crankshaft, not shown, in a conventional manner. Each piston 23 uncovers por-ts 2l in `a cylinder liner I9 when the piston moves to the bottom dead center position.

Gas fuel is introduced into each cylinder liner I9 by a gas fuel nozzle 25, best shown in Figure 2, extending through the air inlet groove l in the cylinder blo-ck and the inner end face of this gas nozzle is provided with an annular groove in which a flexible O ring 26 is placed, which ring engages and is held in compression with the bottom face of an external counterbore 21 around one of the ports of the cylinder liner I9, serving as a gas fuel inlet port and indicated by the reference character 21. The outer end portion of the gas nozzle 25 is provided with an external groove in which another flexible O ring 28 is placed in sealing engagement with the wall of a bore 29 provided in a hand hole cover plate 3| covering a cored hole 33 in the side of the cylinder block I adjacent each cylinder liner I9. A gasket 34 is placed between the hand hole plate and the face of the cylinder block around the hole 33 and a bolt 35 extends through a hole in the plate 3i and is threaded in an opening in the cylinder block to retain the hand hole cover plate tight on the cylinder block. The outer end of the bore 28 of the hand hole plate is greater in diameter and a gas nozzle spring retainer plug 35 is threaded into the outer end thereof and a spring 31 is placed between the plug 36 and an external shoulder 39 provided on the gas nozzle adjacent the outer end thereof to retain the O ring 23 in the groove in the inner end face of the nozzle compressed on the face of the counterbore 2 around the gas port 21' in the cylinder liner. The other ports 2l, as previously mentioned, serve as charging and scavenging air inlet ports. It will be evident that the smaller the diameter of the gas inlet port 2T the lesser the number of crank angle degrees it remains uncovered by the piston when in the lower dead center position. The hand hole cover plates 3i, as best illustrated in Figure 8, are each provided with external hollow flanges 40 extending longitudinally of the engine on either side of and in communication with the enlarged diameter outer end portions of the bores in the hand hole cover plat-es. Flexible gas hose connections |51 are placed between adjacent facing anges 40 of the adjacent hand hole plates 3|. The openings in these hose iianges, are indicated by the reference character 4l, and are shown yextending diametrically into the outer end enlarged diameter portion of the bore 29 in each hand hole cover plate, as best seen in Figure 2. The hose flange M in the hand hole cover plate in one end of the engine is connected to a gas supply pipe connection 55 and the hand hole cover plate flange facing toward the other end of the engine is closed off by means of a pipe plug |55. Clamps, not shown, may be provided for the flexible gas hose connections connected between the flanges on adjacent hand hole cover plates 3|. It will be evident that with the above described hose connections between the hand hole cover plate anges 11! any of these plates may be removed without disturbing the adjacent plates.

A cylinder head 1X3 is secured to the upper end of the cylinder block l Vto form combustion chambers 45 between the inner face of the cylinder head and the head of each engine piston 23. The cylinder head 4S is provided with water jacket spaces if? and an injector mounting sleeve 49 is secured in the head in axial relation with each of the combustion chambers 45. Each of these injector mounting sleeves e9 are secured in aligned bores in the inner and outer end walls of the central water jacket spaces il in the cylinder head in axial relation with each combustion chamber, as best seen in Figure l. One or more poppet type exhaust valves 5t are also shown provided in the cylinder head 4S.

A unit fuel oil injection pump, generally indicated by the character reference 5 I is mounted in each of the injector mounting sleeves 49. The injector pump, as best seen in Figure 6, includes a body 5S having an axial bore therein. A bushing 55 having a smaller diameter end portion 5l is insertable into the bore of the body and an adjacent shoulder on this bushing engages the inner end face of the body 53 around the body bore. An elongated nut 6| is threaded on the body and has an external tapered end surface 62 adapted to be seated on an internal tapered surface of the injector mounting sleeve i9 adjacent the combustion chamber 45. This tapered end surface 62 of the nut 6l is provided with a small diameter axial bore in the outer end and a larger diameter bore coaxial therewith and located inwardly therefrom to form an internal shoulder on which the external flange 64 of an oil fuel injection nozzle d5 is seated. The oil injection nozzle S5 extends through the smaller end bore in the nut ii! and the outer tip portion thereof, which is located in the engine combustion chamber @5, is provided with spray openings l for pressure discharge of fuel oil, The spray openings 6l in the nozzle tip communicate with an atrial core Sii in the oil nozzle extending inwardly from the end adjacent to flange te thereon, Cylindrical valve seats 'H and 'I3 having axiallv ahgned bores are located in an enlarged diameter counterbore in the nut Si' between the fiange of the oil fuel injection nozzle 6% and the inner end face of the bushing- 55, The faces of the bushing 55, valve seats li and i3 and nozzle flange @e are retained in fluid-tight seating engagement when the nut 5i is drawn tight up on the body 53. A valve head l5, valve spring 'il' and spring seat it are located in an enlarged dial eter portion of the bore in the oil fuel nozzle 'd5 with the spring seat '18 seated on an internal shouler "i9 between the adjacent bore portions of the nozzle and the springV 'VI located between the seat and the valve head 75 for urging this head into seating relation with the face of the valve seat 7l surrounding the bore therein. rlhe opposite face of the valve seat ll, in engage ment with valve seat TJ, is provided with a counterhore 3l and a check valve disc 33, having grooves in the edge, is located therein and is moved by oil fuel pressure from the bushing 55 onto the bottom face of the counterbore 6i and fuel oil pressure may pass freely through the edge grooves 85 in the check valve disc S3 and pass through the bore in the valve seat li and unseat the valve head l5 from this seat against the force of the spring il at a preselected fuel oil pressure to then permit passage of high pressure oil fuel through grooves S6, provided in the spring seat 78, and through the connecting bores and spray openings in the oil fuel nozzle and be injected under high pressure directly into the engine combustion chamber 45. Any gas pressure from the engine combustion chamber 45 normally holds the valve head '5 on the seat 'H and. any gas leakage past the valve head and this seat causes the valve disc 83 to be moved into seating relation with valve seat 73 and thereby prevent an entrance of leakage gas from the combustion chamber into bushing 55. A pump plunger 8l is reciprocally and rotatably mounted in the bushing 55 and a fuel oil pumping chamber 88 is formed between the inner end of the plunger 8l and the valve head '15. An oil supply inlet pressure passage 89 and a fuel oil return passage 9i are provided in the body 53 and open into a fuel space 93 formed between the outer surface of the bushing 55 and the surrounding wall of the nut El. The bushing 55 is provided with an upper port 95, serving as a combined oil fuel inlet and by-pass port, and a lower port 91, serving as an oil pressure relief port. Both the upper and lower ports are spaced substantially apart and open directly into the fuel space S3. The outer cylindrical surface of the plunger Si is lapped into the bore of the bushing 55 to minimize fuel leakage therebetween and internal leakage groove d@ provided in the bushing from which leakage passages lil! extend radially from the bottom of this groove to the fuel space 93.' The plunger 81 is normally retained at the outer end of its stroke in the position shown in Figure l, by a spring |03 placed between a lower spring seat member, not shown, lprovided in a body counterbore and a combined spring retainer and plunger guide E95 removably secured to the outer end of the plunger and slidable in the outer end of the body bore as best shown in Figure 1. The plunger guide |95 is engaged by one end of a rocker lever |99 mounted for rocking movement on a rocker shaft |91 which is mounted in a bracket |03 secured to the cylinder head 43. The other end of the rocker lever |06 is operated by a push rod and cam follower mechanism |99 by a cam on a camshaft H3 driven by the engine in conventional manner. Similar rocker levers on the rocker shaft |91 are operated in similar manner from the carnshaft |||J and engage the outer ends of the stems of each of the poppet type exhaust valves, the heads of which are retained seated on valve seats in the cylinder head by springs and spring retainers located on opposite sides of the injector spring |93. As best illustrated in Figure 6 a pinion ||3 is slidable axially and non-rotatably mounted on the plunger 81 and is located in the bore of body 53 between a spacer sleeve ||5 adjacent the outer end face of the bushing 55 and the seat, not shown, of the plunger spring |03, which spring seat is secured in the body bore in any convenient manner to prevent axial movement therein. The pinion l |3 is thus limited in axial movement in the body bore upon reciprocation of the plunger 81. A fuel control rack i1 is slidable in the body 53 and meshes with the pinion |3 to rotate the plunger 31 and vary the eifective stroke thereof, as will be subsequently described. The outer end of each rack ||1 is pivoted to each of a plurality of levers H9, one for each injection pump, which levers are secured on a control shaft |2| rotatably supported in brackets |23 attached to the cylinder head 43. Suitable injection pump holddown means, generally indicated by the character reference |25, are removably secured to the cylinder head for in the injector mounting sleeves 49 in the cylinder head, in the previously described manner, for the injection of oil fuel at high pressure directly 1nto each of the engine cylinder combustion chambers 55.

The plunger B1 is provided with an external fuel metering groove of generally annular form, indicated by the reference character |21. The metering groove is located adjacent the inner end of the plunger and cooperates with the ports 95 and 91 in the bushing 55. Radial fuel passages |29 extend from the bottom of the groove |21 to an axial passage |39 in the plunger extending to the inner end face thereof, as best i1- lustrated in Figure '1. The inner edge of the plunger metering groove |21 includes a helical edge portion 3| and edge portion |33 extending circumferentially normal to the plunger axis, parallel axially extending edge portions |35 and |33 extending outwardly of the inner facerof the plunger and tangent to a semi-circular edge portion |31 forming a no-fuel or engine shut down notch between the helical and circumferential edge portions |3| and |33, The lower edge of the plunger metering groove |21 includes an edge portion |38 parallel to the upper groove edge portion |33 and three helical edge portions |39, |40 and |4| spaced axially outwardly from the edge portion |38 and toward the innerface 7 of the plunger. The positions of theedg' porturn passages 89 and 9| in the bodies of each of v retaining each of the oil fuel injection pumps 5| Y these injection pumps 5| in quantities greater than the maximum amount delivered by the pumps 5| and oil fuel is accordingly also circulated through the fuel spaces 93 in each of these pumps.

As best shown schematically in Figure 8, gas fuel is supplied to the gas fuel nozzles 25 in the engine hand hole cover plates 3| from a source of gas pressure successively through a pressure regulating valve |43, a gas shut-off valve |45, and a gas control valve |41 by means of pipe connections |49, |5|, |53 and |55 and through the previously mentioned hose connections |51. The previously mentioned pipe plug |59 closes off the hose flange 4D of the hand hole cover plate on the opposite end of the engine from the position in which the gas control valve |41 is shown.

The gas control valve |41, as best shown in Figure 3, is secured to a flanged opening |6| of an engine governor, generally indicated by the reference character |62, having a housing |53 secured to the engine block The governor includes the usual spring opposed centrifugally actuated fly Weights, not shown, driven by the engine and operatively connected to rotate a vertical shaft |65 in the governor housing having a lever |99 secured to the upper end of the shaft |55 upon variations in the engine speed in a Well known manner. A floating lever |1| is pivoted by means of the pin |13 at a point intermediate the ends to the governor actuated lever |59. A pin |15 carried by one end of the floating lever |1| projects vertically upward into a slot |11 of a lever |19l secured on the lower end of the vertical shaft I8! rotatable in a sleeve |83 extending upwardly through the opening |6| inthe housing of the gas control valve |4|. The outer end of the sleeve |93 is secured in an opening in a cover plate 89'for this opening in the gas valve housingA |35. A manually operable throttle lever |32 is secured to the upper end of the shaft |8| extending outwardly of the sleeve |93 and cover plate |39. A suitable detent plate |92 is pivotally mounted on a pin |93 secured on the cover plate |89 and engages and positions this throttle lever |9| in an engine shutdown, an engine idle and full speed and load controlling positions in a well known manner. oating lever |1| is pivotally connected by means of a pin |95 to one end of the link |91, the opposite end of which, as best shown in Figure 4, extends transversely through a side opening |93 in the governor housing |33 and a side opening in the cylinder block and is operatively connected to one of the levers H9 on the injector control shaft 12|, as best seen in Figure 1, for operating the racks l1 of the fuel injection pump 5| to simultaneously rotate the pump plungers 91 in these pumps and vary the effective stroke and the amount of fuel injected into engine combustion chamber, in a manner to be subsequently 5 described. The end of the link |91 pivoted to the floating lever |1| is provided with a pin |99 The opposite end of the extending horizontally through a slot in a vertical gas control valve actuating lever pivotally supported intermediate im ends on a horizontal pin 253 secured in opposite walls of the opening |61 of the gas valve housing |95. Gear teeth 205 are formed on the arcuate upper end of the gas control valve actuating lever 20| and these gear teeth mesh with a pinion 201 on the inner end of gas control valve spindle l209. The inner end of gas valve spindle 209 is rotatable by means of a ball bearing 2|l mounted in the inner end of a valve sleeve 2|3. This valve sleeve 2|3 is mounted in gas tight relation in a bore in the gas valve housing |35. The outer end of the gas valve spindle 209 is rotatably mounted in another ball bearing 2li located in the bearing adaption 2 i5 in the housing bore located inwardly of a gas outlet connection 211 which is secured by means of cap screws 2|9 extending through this connection and end plate 236 and threaded to the gas valve housing |85. The bore in valve housing i35 is provided with internal gas outlet grooves 220 and 221 spaced axially apart in the bore around the valve sleeve 2|3 and axial openings 233 lead from the grooves 220 and 22| to aligned holes 234 and 235 provided in the bearing adapter 2|5 and the end plate 235 to the interior of the gas outlet connection 2|1. The gas outlet supply connection |55, shown in Figure 8, is connected to the gas outlet connection 2|1 on the gas control valve. The gas outlet groove 220 in the gas valve housing registers with radial holes 231 in the valve sleeve 2|3 leading to a space 239 around the reduced diameter inner end portion of the valve spindle and the other gas outlet groove 22| in the housing registers with a space 24| between the bearing adapter 2|5 and outer end of the valve sleeve through Which the reduced diameter outer end portion of the valve spindle extends.

As best seen in Figure 5, the gas valve housing |85 is provided with a gas inlet opening 243 to which the gas supply connection |53, shown in Figure 8, is connected. The gas inlet opening 243 in the gas valve housing extends into the housing bore and an external gas inlet groove 245 in the valve sleeve 2|3, intermediate the gas outlet grooves 220 and 22| in the valve housing, registers with the gas inlet opening 243, as best seen in Figure 5. The valve sleeve 2|3 is provided With separate pairs of axially spaced ports 240 located at diametrically opposite points in the bottom of the gas inlet groove 245 shown extended inwardly through the Wall of the sleeve 2|3 surrounding the enlarged diameter central portion of the valve spindle which rotates with slight clearance in the sleeve and is provided with an axially extending diametrically opposite slot 241 movable angularly into and out of register with the diametrically disposed gas inlet ports 246 in the sleeve, as best viewed in Figure 5, to control the amount of gas flowing to the gas outlet holes 231 in the sleeve and spaces 239 and 24| at the ends of the spindle and through the passages 233 in the sleeve and holes 234 and 235 in the bearing adapter and end plate 239 to the gas outlet connection, as best seen in Figure 3. The amount of gas so regulated by the gas control valve then passes to the gas nozzles 25 through the pipe and hose connections |55 and |51 interconnecting the flanges 40 on the engine hand hole cover plates 3|, as best seen in Figure 8. In that equal values of gas pressure are present in spaces 239 and 24| in which the reduced diameter end portions of the valve spindle '209 is located and equal values of gas pressure are present in the diametrically op posite sleeve ports 246 and diametrically oppo site grooves 241 in the spindle the gas control valve spindle is axially and radially balanced.

A stop lever 249, as best seen in Figures 3 and 4, is pinned on a shaft 250 rotatable in the gas valve housing about an axis transverse to the shaft 203 on which the gas control valve actuating lever 20| is pivoted. The upper end of the stop lever 249 is provided with adjacent slots 25| and 252 in which one leg of a U shaped detent lever 253 enters to position the stop lever either out of or into the path of movement of the gas valve actuating lever 20|. The detent 253 is secured on a shaft 255 rotatable in the gas valve housing |85 and a spring 255 is secured between the detent 253 and shaft 203, on which the gas valve actuating lever 20| is pivoted to urge one leg of the detent into either of the slots 25| or 252 therein. As best seen in Figure 4, the shaft 250 on which the stop lever 249 is pinned is also axially adjustable by means of an adjusting screw 251 threaded in the gas valve housing |85 and in engagement with one end of the shaft 250. A spring 259 is located on the shaft 250` between the other side of the hub of the lever 249 and the valve housing to continuously urge the end of the shaft 250 into engagement with the adjusting screw 251. A lock nut 25| is provided on the adjusting screw 251 to lool: it tightly to the gas valve housing. A manually operable lever 253 is secured on the outer end of the shait 250 to rotate the stop lever 249 into a position in the path of movement of the gas control valve actuating lever 20| as determined by the detent 253 entering the slot 252 in the stop lever to limit increasing gas and oil fuel controlling movement of the lever 20| and link |91 by the engine governor, or to move the stop lever into another position out of path of movement of the lever 20|, as determined by the detent 253 entering the slot 25| in the stop lever 249 to thereby permit unrestricted movement of the link |91 and actuating lever 20| between no fuel to maximum fuel positions.

In that the air box 3 in the engine cylinder block is supplied with air under pressure proportional to the speed of the engine driven blower rotors I5 and |1 and in volume greater than that required by the engine at all speeds, as previously mentioned, it is necessary to maintain the gas pressure supplied to the engine through the gas nozzles 25 at a pressure greater than that in the air box at al1 times to prevent air flow from the air box into the gas connections when the gas and air ports in the cylinder liners are uncovered by the engine pistons. The pressure regulating valve |43 is provided for this purpose. This valve is of conventional type and the details of this valve are shown in Figure 9. This valve comprises a valve body 265 having a central gas cavity 261 therein. 'I'his cavity is provided with a shoulder on which a gasket 268 is placed. A baffle plate 269, having a gas inlet orifice 210 and a central opening therein through which a gas valve seat member 21| extends and by -which the baffle is held seated on the gasket 263 by a flange on the outer end of the valve seat member, the inner end of which is threaded into an axial opening in the gas valve body. A gas inlet opening 213 is provided in the valve body, to which the gas supply connection |49, shown in Figure B, is connected. The inlet opening 213 communicates with the space in the valve body below the baiile plate and also with the space above this plate through the inlet orice 210 in the baille plate. The valve seat member has an axial opening 214 extending upwardly from the seating surface on which a valve head 215 is urged into seating relation by a valve spring 215 located between a plug 211 threaded in an axial opening in the lower end of the valve body. A gas outlet opening 219 is provided in the valve body and communicates with the space around the valve head 215 seated on the valve seat 21i. The gas outlet opening is connected to the gas pipe connection II, shown in Figure 8. Radial openings 28| extend from the axial opening 214 in the valve seat member 21| to the space in the valve body below the baffle plate 269 and a valve stem 233 secured to the valve head 215 extends upwardly through the axial opening 214 in the valve seat and an opening in the flange thereof and a head 285 on the upper end of this valve stem is shown engaged with the lower surface of a flexible diaphragm 285 located between a space in the valve body and a valve bonnet 281 secured thereto. A regulating spring 289 is placed between a spring seat 29| in engagement with the upper surface of the diaphragm 285 and a spring seat 253 in engagement with a regulating screw 295 threaded in the'outer end of the valve bonnet to regulate the downward force exerted by the regulating spring on the diaphragm to cause unseating of the valve head 215 and thereby cause an increase in the output gas pressure through the outlet opening 219 in the gas regulating valve. A lock nut 291 on the adjusting screw 295 locks it to the valve bonnet. When the gas pressure acting on the lower-surface of the diaphragm increases, it overcomes the force of the regulating spring and the valve head 215 is moved toward the valve seat 21| by the valve spring 21S to reduce the gas pressure through the regulating valve to a value set by the adjusting screw 295 in a well known manner. This value of gas pressure is slightly above the air pressure in the air box 3 of the engine supplied by the blower rotors when the engine is operating at idle speed. In order to cause an increase in the gas supply pressure to a value greater than that in the engine box 5 for all speeds of the engine and blower driven thereby a pipe connection 299 is connected between the engine air box 3 and the interior of the valve bonnet 281 so that upon an increase in air box pressure applied in addition to that of the regulating spring 28S a corresponding increase in the gas pressure supplied the engine occurs. In this manner the gas pressure is always maintained slightly higher than that in the air box throughout the whole engine speed range so that gas pressure will be supplied through the gas nozzles 25 and ports 2| in the engine cylinder liner at a pressure slightly greater than the air pressure supplied through the other air ports 2| in the cylinder liner and all operating speeds of the engine.

The gas shut off valve |45shown connected between the pressure regulating valve |43 and gas control valve |41 by pipe connections |5| and |53 is a conventional spring closed pressure opened type. An oil pressure connection 36| is connected between the engine oil pressure lubricating system supplied by conventional engine driven lubricating pump and the pressure operated element of the spring closed gas shut ofi valve |45 to maintain gas flow to the gas pressure regulating valve |41 and to the engine only when the engine lubricating oil pressure is at a safe value. When the engine lubricating oil pressure falls below this safe value the valve is spring closed to shut off the gas supply to the engine.

The operation of the engine is as follows: With the engine shut down the operator moves the throttle lever ISI to .the maximum load and speed position of the engine by turning this lever and shaft IBI, to which it is attached, in the direction of the arrow to the increased fuel position as best shown in Figure 3. This causes rotation of the floating lever |1| in the direction of the arrow with reference to the governor actuated lever |65 and shaft |55. This causes the injection pump link |91 and lower end of the gas control lever 2I to be moved to the left as viewed in Figure 4. This movement of the link |91 causes clockwise rotation of the levers I I9 and. injector control shaft |2| as the link is connected, to one of the levers H9 as viewed in Figure 1. This causes inward movement of all of the injector racks H1 connected to the levers H3. This movement of the gas valve actuating lever 25| and injector link ISE is limited by engagement of the actuating lever with the stop lever 249 when the lever 229 is moved to the dual fuel operating position by the manually operable lever 253 which causes the detent 253 to then enter the slot 252 in the stop lever. This inward movement of the injector pump control racks ||1 causes rotation of the injector plungers .81 in the direction of the arrow shown in Figure 6 by the pinion I I3 thereon in engagement with the injector rack and movement of plunger 81 to the right in the direction of the arrow as viewed in Figure '1 to the maximum speed and load dual fuel operating position with respect to the ports and 91 in the injection pump bushings 55, as shown in dotted lines in Figure 7, in which position only sufficient oil fuel is injected into the engine combustion chambers to cause starting of the engine as no gas fuel is supplied to the engine, when stopped, until the lubricating oil pressure builds up to a safe pressure value which then causes opening of the gas shut off valve |25. This movement of the injection pump links |91 by the manual throttle lever |5| also causes the actuating lever 25| of the gas control Valve to move to the maximum gas fuel supply position in which the groove 241 in the spindle 259 of the gas valve is in full register with the gas inlet ports 246 in the sleeve 2I3 of the gas valve, as shown in Figure 3. With the fuel pump plungers 81 in the maximum dual fuel position, as shown in lFigure '1, the upper helical edge |3| of the metering groove |21 of the plunger is moved downwardly by the camshaft I0 slightly before the engine piston reaches the upper dead center position and closes off the oil fuel inlet port 95. Closure of the oil fuel inlet port 95 in the fuel pump bushing 55 traps the oil in the pumping chamber 88 of the fuel injection pump and further downward movement of the plunger 81 compresses the fuel in the pumping chamber and causes the start of oil fuel injection into the combustion chamber to cause ignition of the oil fuel and air compressed therein upon movement of the engine piston on the compression stroke and starting of the engine occurs. Oil fuel injection'continues with continued downward movement of the pump plunger until the lower helical edge |42 of the metering groove |21 of the plunger moves downwardly and uncovers thepressure relief port 91 in the bushing to relieve the oil pressure in the pumping chamber and bring about the end of fuel injection. The high oil fuel pressure in the pumping chamber being relieved through the axial and radial pasansa-sos sages |30 and |29,- metering groove |21 and relief port 91 to the fuel space 93 in the fuel injection pump takes place in conventional manner. It will be noted that the helical edges |3| and |40 controlling the start and finish of fuel injection for dual fuel operation are of equal and opposite inclination and when angular adjustment of the plunger is made for dual fuel operation the start and finish of fuel injection is advanced or retarded an equal amount to maintain the same duration and therefore a constant and limited amount of oil fuel injection for dual fuel operation.

Upon starting of the engine the lubricating oil pressure supplied by the engine driven lubricating pump rises to a safe value and causes this pressure to be applied through the lubricating pressure connection 3M to the actuating member of the gas cut off valve |45 and the cut oil? valve opens to permit gas fuel to then flow through the gas pressure regulating valve |43, gas shut off valve |45, gas, control valve |41 and gas supply connections |49, |l,Y |53, |55, |51 and 4t to the gas nozzles 25 supplying gas to the respective gas ports 2| in the engine cylinder liners at a pressure slightly greater than the pressure of the air in the engine air box 3 which, as explained, is supplied in amountsin excess lto that required by the engine and this air enters the cylinder liners to the other ports 2| therein when the engine piston4 is in the lower dead center position.

In that the gas control valve |61 is limited to the wide open position by the stop lever 249, upon starting of the engine at less than full load the engine speed will increase rapidly andthe engine governor will move the shaft ISS and lever iBS thereon in the direction of the arrow shown in Figure 3 with reference to the pin |15 on one end of the floating lever VH, now held by the manual throttle lever lili in the maximum speed and load dual fuel operating position. This causes the other end of the floating lever to move to the right as viewed in Figure 4 to reduce the amount of gas fuel supplied to the engine and maintain operation of the engine at` the maximum speed for said load on dual fuel. lf the load onthe engine is then increased, the speed will tend to fall olf and thevgovernor will increase `the gas fuel supplied to the engine. Should either the load increase beyond full load or the gas supply fail while operating at maximum speed and load under these conditions (throttle lever 19| in maximum dual fuel setting and lever 263 positioned to enf gage datent 253 in slot 252) the engine speed will decrease because the link` |91 connected to the injection pump and actuating lever 28| of the gas control Valve is then up against the stop lever 2M randono further increase in gas fuel and oil fuel can taire place. o I

Should the load on theengine decrease and the speed increase the governor will rotate the shaft |65 and lever |559 thereon further in the direction of the arrow as shown in Figure 3 and move the injection pumplink |91 further to theright and the gas control actuating lever 20| will be moved further in a cou'nterclockwise direction as viewed in Figure 4 toreducev the gas supply to the engine and reduce the speed. Y

Thisfurther movement of the link 28| also causes the injection pump plungers 8l to be moved to the left as viewed in Figure 7 without reducing the amount of oil fuel injected to cause ignition of the gas and air mixture in the vengine con hustion chamber by causing equal retardation of the sta-rt and also of the nishof oil fuel injection into the engine combustion chambers in the following manner: As the helical out olf edge portion i3| of the pump plunger metering groove |21 cooperates with the inlet port 95 and the helical edge Mil uncovers the relief port Si of the injection pump and, as previously mentioned, these two edges are inclined at equal and opposite helical angles, movement of these edges to the left will delay closure of the inlet port causing the start of fuel injection to he delayed and also to delay the opening of the relief port an equal amount which delays the finish of fuel injection an equal amount thus maintaining the same effective injection stroke of the pump plunger and therefore maintaining constant duration and amount of oil fuel injection; hence, only the time of the start and finish of fuel injection is varied and an equal amount of fuel is injected into the combustion chambers sufcient to cause ignition of the gas air mixture ratio therein when the engine is operating on dual fuel. On account of the start and finish of oil fuel injection to cause ignition being delayed upon increasing engine speeds and decreasing loads, and the start and finish of oil fuel injection being advanced upon decreasing speeds and increasing loads, the same amount of fuel is injected when the engine is operating en dual fuel for all speeds of the engine.

Dual fuel operation is much more economical, especially where cheap gas fuel is available; however, to maintain continuous operation on the diesel cycle with fuel oil only, upon interruption of the gas fuel, the stop lever 269 is manualli7 moved by the manual lever 253 out of the path of movement of the gas valve actuating lever 29| to a position in which the detent 253 enters the slot 25| in the stop lever to permit automatic transition between dual fuel and diesel operation by the action of the governor in the following manner.

With the engine governed at full speed and load and operating on dual fuel should the gas supply fail the engine speed will be reduced and the governorwill move the injector link i5? further to the left and the gas valve spindle 299 clockwise beyond the maximum full speed and load positions for dual fuel operation. l

This further clockwise rotation of the gas valve spindle 2B@ moves the groove il'i therein out of full register with the Vports in the valve sleeve and toward the minimum gas fuel position. This corresponding movement of the injector link 91 moves the injector plunger further to the right as viewed in Figure 7 so that the ports and Q1 then cooperate respectively with 'the helical edge portions iSi and |39 of the plunger ine-tering groove |27 disposed further Vinwardly toward 'the center of the metering groove |21 in the plunger 81. This further 'advances the start and also retards the finish of fuel injection and therefore increases the effective injection stroke of the pump plunger and the duration and amount of fuel and therefore more oil fuel is injected into the engine combustion chambers until the engine speed and load value is increased and maintained substantially the same as when operating on :dual fuel -by action of the engine governor 62.

Upon resumption of the gas fuel supply 'the engine will speedup as then both gas and oil fuel will be supplied and lthe governor will act in reverse manner to move the gas valve back to its full open position and move the injection pump plu-ngers back to the point where the engine is again operating at Vn'iaximum speed and load 'on dual fuel as previously explained. The engine may be operated on dual fuel between maximum speed and load and no load idle speed by movement of the manual throttle lever between the maximum speed and load position and the engine idle position in the opposite direction to that of the arrow shown in Figure 3. This causes rotation of the floating lever |1| with reference to the governor operated lever |69 and causes the gas control valve |41 to move to a partially open position and to also move the injection pump plungers in the direction opposite to the arrow in Figure 7 so that the ports 35 and 91 are positioned to again cooperate with the helical edge portions |3| and |46 located outwardly from the center line of the metering groove |21 in the pump plungers 81 to the right of the diesel operation fuel positions previously described. This further delays the start and also delays the finish of oil fuel injectionr so that a constant pilot amount of oil fuel is injected to ignite the gas and air mixture in the engine combustion chambers to cause part load and speed operation of the engine under control of the governor in a similar manner.

Should it be desired to shut the engine down the manual throttle lever I9| is moved in the opposite direction to the arrow shown in Figure 3 to the no fuel or engine shut down position. This causes the gas control valve |41 to be closed and also causes the injection pump plunger to be moved so that the pump ports 95 and 91 respectively cooperate with the circumferential edge portion |31 of the no fuel or engine shut down notch formed by the edge portion |31 and helical edge portion |4| located furthest from the center of the plunger metering groove and to the left of the idle speed position. These plunger groove edge portions are rarranged to delay the start of fuel injection until after the edge portion 14| opens the relief port 91 so that no fuel is injected into the engine combustion chambers which will cause shut down of the engine.

It will be evident that if the stop lever 245 is held by means of the detent 253 out of blocking relation with respect to the gas valve actuating lever the detent is in the slot 25| of the stop lever 249. This is the diesel operating position of the stop lever, and the manual throttle lever |9| when moved to the full fuel position in maximum speed and load position causes maximum fuel oil injection and reduced gas fuel supply through the gas valve |41 for starting and for operation on oil fuel only when gas fuel is not available. When gas fuel is again available the governor causes transfer between diesel operation and dual fuel operation in the manner previously described.

We claim:

l. In a dual fuel internal combustion engine, engine combustion air supply means, an engine gas supply control valve movable in opposite directions toward closed position from an intermediate open position, an engine oil injection pump having a control element connected to the gas control valve and movable in one direction from an intermediate position to simultaneously vary the time of fuel injection and the amount of gas fuel supplied the eng-ine for operation thereof on both fuels, said control element also being movable in the opposite direction to vary the time land duration of oil fuel injection when gas fuel is not available for operation of the engine on oil fuel only, and an engine governor `14 having a member movable in response variation in engine speed and connected to the control element for automatically controlling transfer between dual and single fuel engine operation.

2. In a dual fuel internal combustion engine, an engine gas fuel pressure supply connection including a pressure responsive gas pressure regulating valve and means biasing said valve closed to prevent gas flow to the engine, an engine combustion air pressure connection, a pressure regulating connection interconnecting the air pressure connection and the pressure responsive gas pressure regulating valve to maintain the engine gas pressure supply greater than the air pressure supply. y

3. In dual fuel compression ignition engine, an engine cylinder having a plurality of circumferentially spaced inlet ports inthe side thereof, a cylinder head, a piston movable in the cylinder controlling opening and closing of the cylinder ports and forming a combustion chamber adjacent the cylinder head, a gas fuel pressure supply connection communicating with the interior. of the cylinder through at least one of the cylinder ports, an air pressure supply connection communicating with the interior of the cylinder through the other cylinder ports, a gas control valve in the gas fuel supply connection, and an oil fuel injection device injecting directly into the combustion chamber to cause ignition of the gas and air therein and to cause operation of the engine on oil fuel when gas fuel is not available. v

4. in a dual fuel compression ignition engine, an engine cylinder having a plurality of circumferentially spaced inlet ports in the side thereof, a cylinder head, a piston movable in the cylinder uncovering the cylinder ports when in rthe outer dead center position and forming av combustion chamber adjacentA thek cylinder :head when in the inner dead center position, a gas fuel nozzle communicating with the interior of the cylinder through at least one cylinder inletport, engine driven. air pressure supply means communicating with the interior of the cylinder through the other cylinder inlet ports, a gas fuel control valve connected to the gas nozzle,A a gas fuel pressure supply connection includinga pressure responsive gas pressure regulating valve connected to the gas control valve, a pressure regulating connection interconnecting the pressure regulating valve and air pressure supply means to regulate the gas pressure supplied the gas nozzle at a value higher than the air pressure supplied the cylinder ports, and an engine oil fuel.

injection pump and `exhaust valve means operable in timed relation with the engine piston and communicating with the engine combustion chamber.

5. In a dual fuel two-cycle compression ignition engine, a cylinder having ports therein, a cylinder head having an exhaust valve anda fuel oil injection pump therein operable in timed relation'by the engine, an' engine piston controlling the opening of the ports during the expansion and compression strokes, a gas control valve communicating with one port, an engine4 driven blower communicating with the other ports and delivering air under pressure in excess of thatrequired by the engine to said ports, said fuel injection pump having a pump rcontrol element movable in opposite directions from'v an intermediate position and having means for varying the start and finish of fuel injectionto supply a-limited and constant amount of oil fuel tocause ignition of the gas and air supplied the engine when said element is moved in one direction and means for varying the start relative to the finish of oil fuel injection to vary the duration and amount of fuel oil injection to cause ignition of the air and oil fuel supplied the engine, when said element is moved in. the opposite direction, an. engine driven governor having a member movable in response to variations, in engine speed and; load, a connection interconnecting said member with the gas control valve and` pump control element to maintain constant speed and load dual fuel and single. fuel operation, manual means operably connected to said connection for varying the speed and load of the engine 6. In a compression ignition engine having a cylinder having ports in the wall, a cylinder head and; a piston controlling the opening and closing of the cylinder ports and forming a combustion chamber with the cylinder head, a gas fuel pres sure connection including a pressure actuated gas pressure regulating valve, a normally closed pressure opened gas fuel valve and a balanced gas supply valve connected between the gas pressure supply connection and at least one cylinder port, an engine driven blower communicating with the other cylinder portsv and supplying air pressure thereto.- in amounts in excess: of engine requirements` throughout the available. speed and load range, a. pressure regulating connection interconnecting the blower outlet to the gas pressure regulating valve to maintain the gas supplied the engine cylinder at a greater pressure than the air pressure supplied thereto, and an oil fuel". injection pump and exhaust valves operable in timed relation with the engine piston and communicating with the combustion chamber.

I In a dual fuel compression ignition engine, a cylinder having ports in the Wall and an air passage communicating therewith including an engine driven blower supplying air under pressure and in amounts greater than maximum en gine requirements, a gas nozzle detachably mounted on the cylinder and communicatingwith one-cylinder port, a gas fuel control valve connected to the gas nozzle, a cylinder head', a reciprocating piston in the cylinder controlling opening oi the ports and forming a combustion chamber in. the cylinder, a iuel oil injection pump comprising a cylinder having axially spaced fuel inlet and relief ports, a plunger reeiprocated the engine in timed relation with the engine and having a fuel metering groove provided with. helical edges and passages leading from the groove to the inner end. face of the plu-nger forming a fuel' pumping chamber in the pump cylinder,V a iuel injection nozzle opening into the engine combustion chamber and conimunicatingY with the fuel pump pumping chamber, a movable control element operably oonnected to the gas control. valveV and also tol the plunger for' angular adjustment of certain helical. edges ci the plunger groove in cooperation with the fuel ports to vary the start andv finishA of fuel injection and maintain a limited constant duration and amount of fuel injection and for variation inthe gas fuel. supplied the engine cylinder to provide variable speed and load operation of the engine on gasand oil iuel, said control member being movable to cause further angular adjustmen-t of other helical edges of the pump plunger groove into cooperation with the vfuel ports to vary the `start and finish of fuel injec-x of fuel injection and for varying the fuel sup plied the engine for corresponding engine operation on oil fuel when gas fuelis not available, a manual throttle lever, an engine driven governor having a member movable in response to engine speed and load variations, a floating lever interconnecting the manual control lever, the governor member and control element for manual control oi variable speed and load of the engine on dual and on single fuel and constant speed and load of the engine by the governor when operating on dual and when operating on single fuel and for automatic transfer between dual and single fuel operation,

8. In a dual fuel engine, an engine gas fuel supply control valve movable in opposite directions toward closed position from a maximum open position, an engine oil fuel injection pump having control means for varying the start and finish of injection, said control means including a member movable through one range to advance and retard both the start and finish of injection in equal amounts and movable through a second range to advance and retard the start relative to the nish of injection, said member being con-l nected to said valve for movement therewith in said one range to control the speed and load of the engine on dual fuel and in said second range to control the engine on oil fuel alone, when gas fuel is not available.

9. In a dual fuel engine, an engine gas, fuel supply control valve movable in opposite directions toward closed position from a full open position, an engine oil fuel injection pump having control means for varying the start and'nish of injection, said control means including a member movable from an intermediate position in one direction to concurrently retard both the start and finish of injection and in the opposite direction to concurrently advance the start and retard the finish of injection, said member being in its intermediate position when said gas valve is in full openV position and. connected to the gas valve for concurrent movement therewith.

lll- In a dual fuel internal combustion engine, an engine gas fuel supply control valve movable in opposite directions toward closed position from an intermediate open position, engine oil fuel injection means including an injection control' element for varying the' startv and finish of injection, said element being movable in one direction from an intermediate position to concur rent-ry retard both the start and finish of injection and in the opposite direction to concurrently advance the start and retard the of injection, a, linie coupling said valve and element llor concurrent. movement and positioning said valve in its intermediate position when said element is in its interi iediate position, a manually movable control member, a floating lever pivotall-y conneet-eel at spaced-apart points to said link and member', anda governor. member movable in opposite directions in response to increasing and decreasing engine speed, said` governor member being pivotally connected to said oating lever intermedi-ate said spaced-apart poi-nts,

il. In. ay dual fuel internal combustion engine, an enginegas fuel supply control valve movable in opposite directions toward closed position froman. intermediate open position, engine oil' fuel injection-,means including an injection. control element ior vai` lug the startend- 1in-ishv of injection,v said element being movable in one direction from an intermediate position to: concurrently retard tion. and thereby vary the duration and amount boththe start and finish ci injection and in the opposite direction to concurrently advance the start and retard the finish of injection, said control valve and element being connected for simultaneous movement of each from their intermediate positions, a manually operable throttle lever movable between closed and open positions, an engine governor member movable in response to engine speed and load variations, and a floating lever interconnecting said governor member, throttle lever and element to position said element in its intermediate position during operation of the engine at rated speed and load with said throttle lever in its open position.

12. In a dual fuel internal combustion engine, an engine gas fuel supply control valve movable in opposite directions toward closed position from an intermediate open position, engine oil fuel injection means including an injection control element for varying the start and nish of injection, said element being movable in one direction from an intermediate position to concurrently retard both the start and finish of injection and in the opposite direction to concurrently advance the start and retard the finish of injection, a link coupling said valve and element for concurrent movement and positioning said valve in its intermediate position When said element is in its intermediate position, an engine governor member movable in response to engine speed variations and connected to said link, and a manually releasable stop movable to a position limiting movement of said element in said opposite direction.

13. In combination with a dual fuel engine having combustion air supercharging means driven by the engine and a source of gas fuel subject to varying delivery pressure to the engine, means for restricting delivery of gas fuel to the engine to a pressure exceeding the pressure of the engine supercharged combustion air, said means comprising a gas passage, a valve controlling said passage, a pressure actuated member operatively connected to the valve and responsive to both said supercharged combustion air pressure and the gas pressure ahead of said valve, and a resiliently yeldable member urging said valve closed.

References Cited in the ile of this patent UNITED STATES PATENTS Number Name Date 1,910,279 Buchi May 23, 1933 1,962,283 Nordberg June 12, 1934 2,294,152 Yates etal Aug. 25, 1942 2,400,219 Barnaby et al May 14, 1946 2,518,400 rIhompson Aug. 8, 1950 2,544,978 Blessing et al Mar. 13, 1951 FOREIGN PATENTS Number Country Date 521,459 Great Britain Nov. 13, 1939 

